1. Field of the Invention
The present invention relates to rotary electric shavers.
2. Prior Art
A conventional typical rotary electric shaver is shown in FIGS. 6 and 7.
The electric shaver 10 is comprised of a main body case 16 and a shaver head 24. The main body case 16 is made of a synthetic resin and is held in the hand during shaving. Inside this main body case 16 is installed a motor 12, a power supply switch 14 and a power supply (not shown in the figures) that supplies electric power to the motor 12, etc. The shaver head 24 is detachably mounted to the upper end of the main body case 16, and it contains outer cutters 18, inner cutters 20, inner cutter bases 22 used for the inner cutters 20, etc.
The electric shaver 10 of FIGS. 6 and 7 is provided with three outer cutters 18 installed in the shaver head 24, and the centers of the outer cutters are positioned roughly at the vertices of an equilateral triangle. However, there is no restrictions on the number of outer cutters 18.
Inner cutter drive shafts 28, made of a synthetic resin and used to transmit the rotational force of the motor 12 to the inner cutters 20 of the shaver head 24, are installed in a number equal to the number of the inner cutters 20. The inner cutter drive shafts 28 protrude from a cutter receiving base 26. The cutter receiving base 26 is made of a synthetic resin and is attached so as to cover the opening in the upper portion of the main body case 16. When the shaver head 24 is attached to the main body case 16 (more specifically to the cutter receiving base 26 of the main body case 16), the tip ends of the inner cutter drive shafts 28 are connected by interlocking engagement to the inner cutter bases 22 to which the inner cutters 20 are attached. As a result, the inner cutters 20 receive a rotational force from the inner cutter drive shafts 28 and are rotated as a unit with the inner cutter drive shafts 28.
The structures of the respective components described above will be detailed below.
First, the shaver head 24 comprises: a cutter frame 30 made of a synthetic resin, outer cutters 18 made of metal, outer cutter holder 32 made of a synthetic resin so as to hold the outer cutters 18, inner cutters 20 made of metal, inner cutter bases 22 made of a synthetic resin and to which the inner cutters 20 are attached, and a cutter retaining plate 34 made of a synthetic resin so as to rotatably hold the inner cutters 20.
The outer cutters 18 are made of metal and formed in the shape of inverted cylindrical bodies. The outer cutters 18 thus have a bottom and a low overall height (so as to be in an inverted saucer or cap shape). The upper-surface portion of each outer cutter which comes into contact with the skin has an annular outer hair entry region V and an annular inner hair entry region W. The hair entry region W is concentric to the inside of the outer hair entry region V. A positioning/engaging portion 36 (formed as an engaging recess for example) is formed in the undersurface of the region X which is inside the inner hair entry region W. The positioning/engaging portion 36 prevents wobbling of the rotating shaft of each inner cutter 20 with respect to the corresponding outer cutter 18 by way of making an interlocking engagement with the end of the inner cutter base.(described later) so that the inner cutter 20 consistently rotates concentrically with the outer cutter 18.
A plurality of hair entry openings 40 are formed in the hair entry regions V and W. In FIG. 6, the hair entry openings 40 are slit-form openings that extend from the outer-circumferential sides to the inner-circumferential sides of the respective hair entry regions V and W. The hair entry openings 40, however, may be scattered small round, oval or slot-form openings.
The surfaces of the respective hair entry regions V and W are made flat. In the outer cutters 18 shown in FIG. 7, the respective hair entry regions V and W are formed so that the hair entry regions are positioned on the same plane.
The outer cutters 18 are set in the outer cutter holder 32 that are made of a synthetic resin so that the outer cutters 18 are not rotatable and the amount of protrusion of the outer cutters 18 from the outer cutter holder 32 is changeable. The outer cutters 18 are tiltable in all directions within a specified angular range inside the outer cutter holder 32.
The outer cutters 18 are mounted in the cutter frame 30 together with the outer cutter holder 32 so that the upper end surfaces of the outer cutters 18 protrude from outer cutter holes 42 formed in the cutter frame 30. The internal diameters of the outer cutter holes 42 are slightly larger than the external diameters of the outer cutters 18. Accordingly, the outer cutters 18 are provided in the cutter frame 30 so that the amount of protrusion of the outer cutters 18 from the cutter frame 30 may change when the outer cutters 18 are moved along the axes of the outer cutter holes 42. The outer cutters 18 are tiltable within a specified angular range in all directions with respect to the axes of the outer cutter holes 42.
The metal inner cutters 20 are U-shaped or Y-shaped inner cutter bodies 20b, and the tip ends thereof are bifurcated and disposed uprightly at equal angular intervals on the outer edge portion of an annular body 20a. Of the respective tip ends formed by the bifurcation of each inner cutter body 20b, the tip end on the outer side contacts the inside surface of the outer hair entry region V of the corresponding outer cutter 18, while the tip end on the inner side contacts the inside surface of the inner hair entry region W of the corresponding outer cutter 18. When the inner cutters 20 rotate, the tip ends of the respective inner cutter bodies 20b are rotated while making sliding contact with the inside surfaces of the respective hair entry regions V and W of the corresponding outer cutters 18.
The cutter retaining plate 34 holds the inner cutters 20. The retaining plate 34, made of a synthetic resin material, is comprised of attachment rings 34a, which are equal in number to the inner cutters 20, and a supporting frame 34b, which connects these attachment rings 34a into an integral unit. Anchoring portions 48 are disposed on the inner circumferential surfaces of the attachment rings 34a so as to protrude toward the axes of the attachment rings 34a. An attachment screw 50, which is used to attach the cutter retaining plate 34 to the cutter frame 30 is disposed in the center of the cutter retaining plate 34.
The structure for holding the inner cutters 20 by the cutter retaining plate 34 will be described below.
The inner cutter bases 22 to which the inner cutters 20 are fastened are formed in a columnar shape using a synthetic resin material. An inner cutter 20 is fastened to one end (the upper end in FIG. 7) of each inner cutter base 22; and a flange 52 is formed around the outer circumferential surface of the other end (the lower end in FIG. 7) of each inner cutter base 22. A positioning/engaging portion 38 (formed as an engaging projection, for example) which engages with a positioning/engaging portion 36 formed in the corresponding outer cutter 18 is formed in the center of the first end of each inner cutter base 22. The radius of the flange 52 of each inner cutter base 22 is greater than the distance from axis (center) of the corresponding attachment ring 34a to the inside tip end of the anchoring portions 48 formed on the inner circumferential surface of the attachment ring 34a. Also, the radius of the portions of the inner cutter base 22 other than the flange 52 is smaller than the distance from the axis of the attachment ring 34a to the inside tip end the anchoring portion 48. An engaging recess 56 is formed on the end surface of the other end of each inner cutter base 22 so that an engaging projection 54 formed on the tip end of the corresponding inner cutter drive shaft 28 is inserted in this engaging recess 56.
When each inner cutter 20 is fastened to the corresponding inner cutter base 22, the annular body 20a of the inner cutter 20 is first fastened to the first end of the inner cutter base 22 so that the inner cutter 20 is fastened to the inner cutter base 22. As a result, the positioning/engaging portion 38 protrudes from the inside of the annular body 20a. 
Afterward, the inner cutter base 22 is inserted into the corresponding attachment ring 34a of the cutter retaining plate 34 from the other end. In this case, the anchoring portions 48 of the attachment ring 34a interferes with the flange 52 of the inner cutter base 22. Thus, the flange 52 is inserted into the attachment ring 34a while causing the anchoring portions 48 to bend slightly.
As a result, the inner cutter 20, that has a radius greater than the distance from the axis of the attachment ring 34a to the inside tip ends of the anchoring portions 48, and the flange 52 of the inner cutter base 22 are positioned on both sides of the attachment ring 34a with the attachment ring 34a sandwiched in between. The inner cutter 20 is thus held in the attachment ring 34a so that the inner cutter 20 is retained and not to slip out. The inner cutter 20 is held so that it is rotatable inside the attachment ring 34a, that it is tiltable in all directions with respect to the axis of the attachment ring 34a, and that it is slidable in the direction of the axis.
Next, how the outer cutters 18 and inner cutters 20 are attached to the cutter frame 30 will be described.
First, the outer cutter holder 32 to which the outer cutters 18 are attached is mounted in the cutter frame 30. Afterward, the cutter retaining plate 34 holding the inner cutters 20 is attached to the cutter frame 30 by screwing the attachment screw 50 into an internally threaded screw hole 30a formed inside the cutter frame 30. As a result, the outer cutter holder 32 is pressed by the cutter retaining plate 34, and the outer cutters 18 and inner cutters 20 are held to the cutter frame 30 so as not to slip out.
By way of turning the attachment screw 50 in the reverse direction, the inner cutters 20 is removed as a unit with the cutter retaining plate 34, and the outer cutters 18 is removed as a unit with the outer cutter holder 32.
Next, the main body case 16 that includes the inner cutter drive shafts 28 will be described.
The main body case 16 is formed as a cylinder having an open top and a closed bottom. A motor 12, a battery (not shown), a control circuit and other constituting elements are installed inside this main body case 16.
A gear shaft receiving plate 58 is installed inside the main body case 16 near the rim of the opening in the main body case 16. The motor 12 is fastened to the gear shaft receiving plate 58 at right angles with reference to the output shaft 12a of the motor 12 protruding. Main supporting shafts 60 are fastened to the gear shaft receiving plate 58 adjacent to the output shaft 12a and parallel to the output shaft 12a in positions corresponding to the outer cutters 18. A motor gear 62 is attached to the output shaft 12a of the motor 12. Inner cutter driving gears 64 made of a synthetic resin are rotatably attached to the main supporting shafts 60 so that these inner cutter driving gears 64 engage with the motor gear 62. At the centers of the upper surfaces of the inner cutter driving gears 64, cylindrical coverings 65 for covering the main supporting shafts 60 that are passed through the inner cutter driving gears 64 are integrally formed so as to be upright with respect to the inner cutter driving gears 64. Furthermore, shaft anchoring projections 70 are formed so as to surround the coverings 65.
A cutter receiving base 26 is mounted in the upper end opening of the main body case 16 so that the receiving base 26 is positioned above the gear shaft receiving plate 58 and close off the upper end opening. Drive shaft holes 66 are formed coaxially with the axes of the respective main supporting shafts 60 in the cutter receiving base 26.
The inner cutter drive shafts 28 are positioned so that the tip ends of these shafts protrude from the drive shaft holes 66. A plurality of engagement projections 68 are formed on the outer circumferential surfaces of the lower ends of the inner cutter drive shafts 28. These engagement projections 68 respectively engage with a plurality of shaft anchoring projections 70 which are formed on the upper surfaces of the inner cutter driving gears 64 so that the engagement projections 68 surround the lower portions of the inner cutter drive shafts 28. More specifically, these components are arranged so that the inner cutter drive shafts 28 (only one drive shaft shown in FIG. 7) are rotatable as a unit with the inner cutter driving gears 64, the inner cutter drive shafts 28 are tiltable in all directions with respect to the axes of the inner cutter driving gears 64 (which are also the axes of the main supporting shafts 60), and the inner cutter drive shafts 28 are movable a specified distance along their axes.
Furthermore, engaging projections 54 are formed on the closed upper ends of the inner cutter drive shafts 28, and the lower ends of the inner cutter drive shafts 28 are formed open. The coverings 65 formed on the inner cutter driving gears 64 are inserted into the interiors of the inner cutter drive shafts 28 from the lower-end openings.
Outside inner cutter member springs (called xe2x80x9couter springsxe2x80x9d) 72 are installed inside the inner cutter drive shafts 28. The outer springs (coil springs) 72 are fitted over the coverings 65. These outer springs 72 are installed in a compressed state between the inside upper surface of the inner cutter drive shafts 28 and the upper surfaces of the inner cutter driving gears 64. Thus, the outer springs 72 constantly urge the inner cutter drive shafts 28 upward relative to the inner cutter driving gears 64. The inner cutter drive shafts 28 are driven by the outer springs 72 in a direction that causes the inner cutter drive shafts 28 to move away from the inner cutter driving gears 64. However, when the inner cutter drive shafts 28 are separated from the inner cutter driving gears 64 by a specified distance, the engagement projections 68 formed on the outer circumferential surfaces of the lower ends of the inner cutter drive shafts 28 come to engage with the shaft anchoring projections 70 formed on the upper surfaces of the inner cutter driving gears 64. Thus, the inner cutter driving gears 64 are prevented from slipping off of the coverings 65.
With the above-described structures of the shaver head 24 and main body case 16, when the shaver head 24 is attached to the main body case 16, the engaging projections 54 of the inner cutter drive shafts 28 (only one drive shaft 28 shown in FIG. 7) fit into the engaging recesses 56 of the lower ends of the inner cutter bases 22. In addition, the inner cutter drive shafts 28 are pressed by the inner cutter bases 22, and the inner cutter drive shafts 28 are pushed slightly into the interior of the cutter receiving base 26 against the driving force of the outer springs 72.
In this state, the driving force of the outer springs 72 is transmitted to the inner cutters 20 from the inner cutter drive shafts 28 via the inner cutter bases 22, so that the inner cutters 20 are pushed toward the outer cutters 18. As a result, the tip ends of the inner cutter bodies 20b of the inner cutters 20 make a close contact with the inside circumferential surfaces of the outer cutters 18. Also, the outer cutters 18 are pushed by the inner cutters 20 so that the outer cutters 18 are in a state of maximum protrusion from the cutter frame 30.
When hairs are shaved using the electric shaver 10 as described above, the main body case 16 is held in the hand, and the outer cutters 18 protruding from the surface of the cutter frame 30 are pressed against the skin. In this case, in conformity with the shape of the skin, the outer cutters 18 are moved toward the interior of the cutter frame 30 against the driving force of the outer springs 72 and the elastic force of the retaining plate 34 (i.e., the amount of protrusion from the cutter frame 30 varies). The outer cutters 18 also tilt in conformity with the shape of the skin. Thus, the respective hair entry regions V and W formed in the outer cutters 18 snugly fit against the skin. Even when the outer cutters 18 tilt with respect to the cutter frame 30, the positioning/engaging portions 38 formed on the ends of the inner cutter bases 22 are engaged in an interlocking manner with the positioning/engaging portions 36 formed in the outer cutters 18. Accordingly, the inner cutters 20 also tilt in accordance with the inclination of the outer cutters 18, so that the respective tip ends of the inner cutter bodies 20b of the inner cutters 20 are maintained in a close contact with the inside surfaces of the respective hair entry regions V and W of the outer cutters 18.
Generally speaking, the shape of the human face, e.g., in the cheeks, jaw and throat where hairs grow, is rich in variation. In some cases, the close contact with the skin (as viewed from the standpoint of the outer cutters 18 overall) may be more improved if the inner hair entry regions W protrude further from the surface of the cutter frame 30 than the outer hair entry regions V; or conversely, if the inner hair entry regions W are sunk further inward than the outer hair entry regions V, the conditions of shaving are improved. Furthermore, an overall close contact of the outer cutters 18 with the skin is sometimes better if the inner hair entry regions W are tilted with respect to the outer hair entry regions V.
However, in the conventional rotary electric shaver described above, each of the outer cutters 18 is a single cylindrical body, and each of the inner cutters 20 also has a similar integral structure. As a result, the positional relationship of the outer hair entry regions V and inner hair entry regions W is fixed; and the shape of the contact surfaces of the outer cutters 18 that contact the skin cannot vary in accordance with the shape of the skin (i.e., the inner hair entry regions W cannot protrude and retract, or tilt with respect to the outer hair entry regions V). Thus, the better shaving conditions described above cannot necessarily be realized.
Accordingly, the present invention is to solve the above-described problems with prior art shavers.
The object of the present invention is to provide a rotary electric shaver in which the shape of the contact surfaces of the outer cutters that contact the skin during shaving can vary in accordance with changes in the shape of the skin contacted by the outer cutters.
The above-described object is accomplished by a unique structure of the present invention that has the structure described below:
The rotary electric shaver of the present invention is characterized in that the shaver comprises:
an inside outer-cutter member,
a cylindrical outside outer-cutter member which concentrically surrounds the inside outer-cutter member and is mounted in a cutter frame so that the end surfaces of the outside and inside outer-cutter members protrude from an outer cutter hole formed in the cutter frame,
an inside inner-cutter member which makes sliding contact with the inside outer-cutter member, and
an outside inner-cutter member which makes sliding contact with the outside outer-cutter member, and wherein
the outside outer-cutter member is provided in the cutter frame so that the outside outer-cutter member tiltable with respect to the axis of the outer cutter hole and is movable along the axis, and
the inside outer-cutter member is connected to the outside outer-cutter member so that the inside outer-cutter member is tiltable with respect to the axis of the outside outer-cutter member and is movable along the axis,
the inside inner-cutter member is engaged with the inside outer-cutter member so that the inside inner-cutter member is rotatable with the axes of the inside inner-cutter member and inside outer-cutter member being coincide with each other, and
the outside inner-cutter member is engaged with the outside outer-cutter member so that the outside inner-cutter member is rotatable with the axes of the outside inner-cutter member and outside outer-cutter member being coincide with each other.
As a result, if the shape of the skin contacted by the outer cutters (each comprising the inside outer-cutter member and the cylindrical outside outer-cutter member) varies, the outside outer-cutter members and inside outer-cutter members are moved independently in conformity with the shape of the skin. Thus, the respective contact surfaces of these outer cutters make a snug contact more easily with the skin, and improved shaving is performed.